Imaging pyrometry of laser-heated sapphire

A long-wave infrared camera was used in an imaging pyrometric mode to deter mine the spatially resolved outer surface temperature of sapphire samples h eated with a carbon dioxide (CO2) laser. Tests were conducted by APL at the Laser Hardened Materials Evaluation Laboratory, Wright-Patterson Air Force Base, Ohio. Sapphire disks were assessed first to demonstrate the CO2 lase r heating technique and the capabilities of the infrared pyrometry system. Additional testing was conducted on sapphire domes that are candidates for infrared seeker windows. The laser heating profile presented (written) to e ach dome during testing simulated the aerothermal heating profiles that wer e observed in hypersonic wind tunnel tests conducted in APL's Advanced Tech nology Development Laboratory. Only sapphire disk test results are presente d here, although both disk and dome testing protocols are discussed.